Bacteriological Safety of Swine Carcasses Treated with Reconditioned Water

Swine carcass microflora were evaluated for selected foodborne pathogens after exposure to reconditioned water during scalding, dehairing, and polishing operations. Reused water had been reconditioned and chlorinated. Rodac plates applied to hams were used to assess carcass microflora. Water samples were enumerated using membrane filtration or spiral plating. Sampling was at mid-week throughout the year. Total aerobic plate counts on hams were unaffected by treating with potable or reconditioned waters. No differences were observed for staphylococci, enterics, fecal streptococci, Listeria monocytogenes, coliforms, and Aeromonas levels. A preevisceration potable water carcass wash reduced the bacterial load, regardless of initial treatment. Bacterial counts on carcasses paralleled those in water. Reuse is an alternative to potable water for initial slaughter operations without diminishing bacteriologic safety.     

Radon track imaging in CR-39 plastic detectors using confocal scanning laser microscopy

Confocal scanning laser microscopy (CSLM) has been used to provide the first images of radon track populations in two external CR-39 plastic detectors. Measurements of variables including track area distribution and estimates of the angle of track inclination (dip) derived from surface CSLM sections are presented. CSLM depth slices, combined with three-dimensional (3D) visualization techniques, provide a new, non-destructive way of examining the 2D and 3D geometry of the etched tracks within solid-state nuclear track detectors that may prove useful in complementing existing optical microscopy methods.     

Transfer-function matrix synthesis by matrix generalized inverses

The matrix generalized inverse provides a symbolism for establishing the consistency and finding the solution of a system of linear algebraic equations. This concept is employed to find a control law for a linear time-invariant control system which causes the transfer-function matrix of the resulting system to be a specified function of s.     

On the application of matrix generalized inverses to the construction of inverse systems

A discrete-time fast regulator with fast observer is considered in this paper. The system is assumed as a linear time-invariant nth order r-input, m-output system. Complete controllability and complete observability are assumed. No assumptions are made on the non-singularity of the system matrix and integrality of n/r and n/m. It is shown that the fast regulator with fast observer transfers any initial state to the origin within the number of steps equal to the sum of observability and controllability indices. Simple design methods for fast regulator and fast observer are presented. Also, it is illustrated geometrically how the state point is transferred to a subspace with successively decreased dimension for each step until it arrives at the origin.     

Control of Enzymatic Browning in Pre-peeled Potatoes by Surface Digestion

Feasibility of lye digestion to remove surface tissues from peeled potatoes prior to treatment with browning inhibitors to extend shelf-life was investigated. Russet and round-white potatoes were digested in 14–20% NaOH at 35–55°C for 1–13 min. After removal of digested tissue, tubers were treated with ascorbic acid-based browning inhibitor. Browning was measured by tristimulus calorimetry. Digestion extended shelf-life of high pressure steam- and abrasion-peeled potatoes to 13–15 days at 4°C, compared to 3–11 days for undigested controls. Digestion resulted in weight losses of 12–26%, depending on treatment conditions. Lye digestion in conjunction with conventional browning inhibitors represents a viable alternative to sulfiting pre-peeled potatoes.     

Mass Flow and Energy Use During Orange Peel Oil Recovery

Electrical energy consumption and oil recovery were measured during operation of a commercial citrus peel oil centrifugation process. Two parts of a centrifuge's electrical consumption were identified: regular operation and the discharge cycle. During discharge cycles, the electrical energy ranged from 125–189% of the steady-state values. Energy costs were computed for the desludger and polisher centrifuges. Direct electrical costs for the oil mill totaled 0.67/kg oil recovered. Electrical costs calculated for finishing and dewaxing totaled 0.5/kg oil. Actual oil yield (1.1 kg/t) was only 20% of the total in the fruit. A major source of oil loss occurred during extraction from the fruit, where less than 50% of the oil was actually extracted into the dilute emulsion. Inefficient operation of the centrifuges accounted for most of the remaining losses.     

Visible Spectroscopy of Irradiated High-Alkali Borate and Mixed-Alkali Phosphate Glasses

Expectations of increased stability for trapped electrons in high-alkali glasses, based on extrapolations from observations on low-alkali borate glasses, are not borne out. In 69Na₂O-31B₂O₃ glass, electron centers have approximately the same thermal stability as in Na₂O·2B₂O₃ glass. In Na₂Oplus;P₂O₅ glasses the lifetimes, 3 · 0.5 μS, of transiently trapped electrons as well as their absorption spectra prove to be independent of increase of Na₂O content from 50 to 60 mol%. The same composition change destabilizes "permanent" hole centers. Exchange of Na₂O with K₂O in the metaphosphate glass also has no effect on the trapped electron lifetime. Small linear shifts in the trapped-hole absorption peak wavelengths are observed in the latter case. The most important positive finding in the phosphate glasses is a pronounced mixed-alkali effect on the yield of transiently trapped electrons and holes and of permanently trapped holes. The yield is a minimum at Na:K=1:1, due either to the elimination of trap sites or to the reduction of alkali ion mobilities which play a role in trap formation.     

ENERGY CONSERVATION IN DRYING OF FRUITS IN TUNNEL DEHYDRATORS

This study reports the energy use and thermal losses associated with tunnel dehydrators and discusses methods of increasing energy efficiency. These dehydrators can operate with an efficiency of water removal greater than 50%. It is shown that energy conservation techniques such as minimizing air leakage, increasing air recirculation, utilizing a furnace heat shield to prevent heat losses, and maximizing input can result in significant energy savings.